The present invention relates to a water treatment method and a water treatment system, and relates to, as an example, a water treatment method and a water treatment system for the entire plant including production devices. The present invention also relates to, as an example, a water treatment method and a water treatment system in which air micro-nano bubbles and nitrogen micro-nano bubbles are effectively generated to be used inside the plant as well as to be used in pretreatment of treatment water in waste water treatment. The present invention also relates to, as an example, a water treatment system and a water treatment method relating to the entire plant in which treatment water containing micro-nano bubbles is pretreated before being introduced into a waste water treatment device so that the efficiency of the waste water treatment device is considerably enhanced, by which the entire waste water treatment device can be downsized and the quality of treated water can be increased.
In the water treatment methods and water treatment devices, some methods and devices have conventionally been present as general pretreatment methods and pretreatment devices.
For example, the treatments performed by a pretreatment device in a biological treatment device include settling, filtration, pH control, ozone oxidation and absorption. The purpose of the pretreatment device is to reduce biological, chemical or physical loads of a water treatment device in the subsequent step, and therefore, downsizing of the water treatment device, reduction in running costs, increase in water quality of treated water coming from the water treatment device and the like can be expected.
However, the action by the conventional pretreatment does not implement a function to considerably increase the dissolved oxygen concentration in the treatment water and to sustain the dissolved oxygen concentration for a long period of time till the subsequent step nor a function to considerably increase the dissolved oxygen concentration in the treatment water and to dramatically enhance the reaction efficiency. In a word, the action does not go much beyond general aeration as pretreatment by a blower.
Moreover, a method and a device for using nano bubbles have been disclosed in JP 2004-121962 A as prior art.
It has been disclosed in this prior art to utilize characteristics such as a surface activity effect and a sterilization effect by implementation of the decrease of buoyancy, the increase of a surface area, the intensification of surface activity, the generation of a local high pressure field, and electrostatic polarization in the nano bubbles. More specifically, it has been disclosed that with mutual association of the characteristics, it becomes possible to clean various objects with a high function and a low environmental load and to purify polluted water by the function to adsorb pollution components as well as by the function of high speed cleaning and sterilization of object surfaces.
Further, a method for generating nano air bubbles as another prior art has been disclosed in JP 2003-334548 A.
In this prior art, it has been disclosed that the method is composed of a process (1) for decomposing a part of liquid into gas in the liquid, a process (2) for applying ultrasonic waves in the liquid or processes (3) for decomposing a part of liquid into gas and for applying ultrasonic waves.
With research and development of the effects and the functions of the micro-nano bubbles being conducted, methods and devices for effectively generating and effectively using micro-nano bubbles are being demanded.